Simultaneous determination of amoxicillin and prednisolone in bovine milk using ultra-high performance liquid chromatography tandem mass spectrometry.

A rapid and sensitive ultra-high performance liquid chromatography tandem mass spectrometric method was developed for simultaneous quantification of amoxicillin and prednisolone in bovine milk. In this method, amoxicillin, prednisolone and the internal standards penicillin G-d(7) (for amoxicillin) and prednisolone-d(6) were extracted from bovine milk using acetonitrile. The C(18) solid phase extraction cartridges were selected for cleaning-up the extracts. The analytes were determined using a triple quadrupole mass spectrometry in positive electrospray ionization and multiple reaction monitoring mode. Calibration curves were linear over a concentration range of 2-1000 μg/kg for the analytes. The mean recoveries were 89.2-92.3% for amoxicillin and 98.7-102.3% for prednisolone. Limits of detection were 0.5 μg/kg for the analytes, and the limits of quantitation were 2 μg/kg. Decision limit (CCα) and detection capability (CCβ) have also been estimated for each analyte. The method was validated according to the Commission Decision 2002/657/EC and successfully applied to the analysis of amoxicillin and prednisolone in real samples.